Too much coolant causing low coolant alarm?

If your injector cups are leaking, you smell diesel in your coolant.

Scottiemom wrote:
When we started getting that alarm, we too had plenty of coolant in the reservoir. But we still got a low coolant alarm. Sometimes we would go into limp mode for a few minutes, then she would start running like the wind and run all day. Next day, hard to start, back to low coolant levels, etc. Took it to SEVEN Cat garages in different states as we were fulltiming and traveling and no one could find a problem. Took it to the Gaffney service center. . . nothing wrong.

This went on for nearly a year while we were fulltiming. Finally something happened and coolant blew out the overflow and all over the toad and back of the motorhome. (Phaeton) Took it to Cat in Edinburg, Texas, and the tech said, "Your injector cup seals, 1 or more, are bad and allowing diesel fuel to mix with the coolant." Hence the sensor (which we had replaced) thought the coolant was low when in fact the reservoir was overflowing. Had all the injector cup seals replaced. Problem solved and never another problem while we owned the coach. They were the only ones from then on who did our service work.

Dale

Thanks for the reply. I hope that is not the issue, but we'll see. I have a Cummins however, but I know they have the same parts. And when the alarm first came on the reservoir was a bit low, so I topped it off. I have since drained the reservoir twice and did not see anything in the coolant that should not be there. Yet anyway.

So basically you lucked out and came across a tech who had seen this relatively uncommon problem before, whereas the other techs who looked at it previous were following normal troubleshooting processes and finding no issues.

I'm just saying I don't think you can blame the previous techs for not finding the problem. They're not superheroes.

When we started getting that alarm, we too had plenty of coolant in the reservoir. But we still got a low coolant alarm. Sometimes we would go into limp mode for a few minutes, then she would start running like the wind and run all day. Next day, hard to start, back to low coolant levels, etc. Took it to SEVEN Cat garages in different states as we were fulltiming and traveling and no one could find a problem. Took it to the Gaffney service center. . . nothing wrong.

This went on for nearly a year while we were fulltiming. Finally something happened and coolant blew out the overflow and all over the toad and back of the motorhome. (Phaeton) Took it to Cat in Edinburg, Texas, and the tech said, "Your injector cup seals, 1 or more, are bad and allowing diesel fuel to mix with the coolant." Hence the sensor (which we had replaced) thought the coolant was low when in fact the reservoir was overflowing. Had all the injector cup seals replaced. Problem solved and never another problem while we owned the coach. They were the only ones from then on who did our service work.

Dale

My first guess is there is an air pocket! How much liquid is in the pressurized "overflow" tank?